How to Insulate a Room With Aluminum Foil

Aluminum foil will completely block out sunlight because it's opaque and reflect it because it's silver. Many commercial insulators include aluminum foil. You can use the foil rolls from the grocery store to quickly and cheaply insulate any room in your home, especially in the hot summertime.

Things You'll Need

Aluminum foil

Adhesive tape

Determine how much aluminum foil you need for each room in your home. No one window should take a full roll, but a full-plat window could come close. The amount of foil also depends on how many windows you have.

Pull off strips of the foil long enough to cover one window end to the other. You'll want to go 6 inches to 1 foot past the window's actual height or width. Tear off enough strips to cover the whole window.

Tape the foil strips onto the wall, covering up the window one section at a time. You should use duct tape or some other sturdy adhesive. Tape down every edge along the wall for holding strength and to seal out the light.

Seal with more tape any places between strips along the windows where light comes through. This step may not be necessary if only very small cracks of light are shining through.

Repeat the process for all windows in rooms you want insulated. The foil will block out the sunlight, reduce the heat buildup, help keep the rooms cool and lower your energy bills.

Tips & Warnings

You should secure the foil on the inside wall away from the window glass. Putting it on the glass itself may violate a fire code or city ordinance.

Since this will darken the rooms, you will likely need to have lights on more often. This should still lower your energy bills, especially if you are using energy-efficient light bulbs.

Keeping the foil up during the colder months is up to you. Letting the sun come in could help warm the home. But if the edges are completely sealed, it can help keep warm air in and cold air out.